This invention relates generally to drills and more specifically to an apparatus for precisely installing a plastic depth ring over the shank of a drill.
Manufacturers of electronic equipment routinely employ solid carbide drills for drilling holes in printed circuit boards used in connection with electronic circuits. These drills are typically 11/2" in length and have various flute diameters but a common 1/8" shank diameter. Drills having flute diameter sizes from #80 (0.0135") through #31 (0.1200") are generally referred to as small drills, while those having flute diameters of 1/8" through 1/4" are generally referred to as large drills.
Prior to using such drills in circuit board drilling operations it is necessary to press a plastic depth ring over the shank of each drill at a critically specified distance from the drill point. The depth ring determines the depth to which a given hole will be drilled in a circuit board by the automatic drilling machines in which the ringed drills are used. Due to the high speeds at which such drills are operated, it is necessary to sharpen them at frequent intervals. In order to sharpen these drills the plastic depth rings must first be removed.
It has been observed that prior art methods employed in the installation and removal of the depth rings from such drills have resulted in damage to the drill points. This damage is typically manifested as chipping or breaking and significantly shortens the life of a drill. In addition, damage done to a newly sharpened drill during the installation of a plastic depth ring renders that drill all but useless for drilling operations until it has been resharpened. Oftentimes, damage to a drill will go undetected for a period of time, resulting in poor hole quality and a high percentage of scrap circuit boards.
A further disadvantage of prior art methods for installing plastic depth rings is the associated loose tolerance to which the rings are installed. In the event the depth ring is installed too far from the drill point, the drill will likely be damaged by contacting the steel table of the drilling machine during drilling operations.
It is therefore the principal object of the present invention to provide an apparatus for quickly and precisely installing depth rings on drills without thereby damaging any cutting edges of the drills and for similarly quickly removing those depth rings, again without thereby causing damage to the drills.
This and other incidental objects are accomplished in accordance with the illustrated preferred embodiment of the present invention by providing a base plate on which are mounted a pair of installation mechanisms for installing depth rings on both small and large drills, respectively, and a removal mechanism for removing depth rings from drills on which they have been previously installed. Each of the setting mechanisms includes a dial indicator for very accurately positioning the depth rings as they are being installed on the drills.